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Custom State Descriptions

Some standard Android controls also contain state which they expose to Accessibility Services. For example, a CheckBox control has two states announced by TalkBack as "Checked" and "Not checked". Similarly, the SwitchCompat and SwitchMaterial controls have the states "ON" and "OFF". It is possible to customize these state descriptions to improve the user experience in TalkBack.

To change the state description of a stateful View control, use ViewCompat.setStateDescription() as follows:

ViewCompat.setStateDescription(
    binding.alarmCheckbox,
    if (binding.alarmCheckbox.checkedState == MaterialCheckBox.STATE_CHECKED)
        "Activated" 
    else 
        "Deactivated"
)

This CheckBox will announce its state in TalkBack as "Activated" or "Deactivated" instead of "Checked" and "Not checked".

It is also often appropriate to customize the standard click action description to match the state being changed to, instead of the standard "Double-tap to toggle" announcement.

binding.alarmCheckbox.accessibilityDelegate = object : View.AccessibilityDelegate() {
    override fun onInitializeAccessibilityNodeInfo(
        host: View,
        info: AccessibilityNodeInfo
    ) {
        super.onInitializeAccessibilityNodeInfo(host, info)
        info.addAction(
            AccessibilityAction(
                AccessibilityAction.ACTION_CLICK.getId(),
            if (binding.alarmCheckbox.checkedState == MaterialCheckBox.STATE_CHECKED)
                "Deactivate alarm" 
            else 
                "Activate alarm"
            )
        )
    }
}

This CheckBox will now announce its standard click action as "Double-tap to activate alarm" if unchecked and "Double-tap to deactivate alarm" if checked.

Although ViewCompat.setStateDescription() does not work successfully on all Android platforms, when it does not, the standard state description text is announced. So attempting to improve the user experience by customizing the state description does no harm.

(Note: The hard-coded text shown in these examples is only used for simplicity. Always use externalized string resource references in actual code.)

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